Exhaust valve with leak detector



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J. M. CAMPBELL Dec. 12, 1950 EXHAUST vALvx-z wrm LEAx DETECTOR Filed March 29, 1944 2 Sheets-Sheet 2 ATTORNEY Patented Dec. 12, 1,9570

UNITED STATES PATENT OFFICE EXHAUST VALVE WITH LEAK DETECTR Application March 29, 1944, Serial No. 528,570

10 Claims.

This invention relates to machines for gas filling and/or exhausting hollow bodies and particularly to such used for the manufacture of iiuorescent lamps and similar devices.

The primary object of my invention, generally considered, is to provide a leak detector for exhaust machines comprising a pressure-responsive circuit making and breaking device, such as mercury U tube with contacts which are opened or closed in accordance with the vacuum condition in the exhaust line, and a relay to prevent breaking of said circuit, as by opening of such mercury contacts while power is on them, in order to thereby avoid damage, such as cracking the glass-to-metal seal or evolving gases which change the sensitivity of said U tube.

Another object of my invention is to provide a method for detecting leaks comprising an energizing circuit to a mercury U tube with contacts in which said tube is connected to the exhaust system, so that a leak causes closing of said contacts and energization of a leak detector, involving snorting out of said contacts upon the development of a leak so that when the vacuum is restored no spark'occurs upon opening said contacts.

A further object of my invention is the provision ofl an exhaust machine with a mercury U tube having contacts connected to the line in one position and a normally-closed solenoidactuated valve making said line a dead port, a circuit to said contacts controlled by a cam switch, a relay in said circuit shorting said mercury contacts when said circuit is energized, in order to avoid the formation of a spark when said contacts are opened, and a leak indicator and said valve controlled by said mercury U tube contacts, whereby upon the development of a leak the mercury in said tube closes the circuit through said contacts, energizing the relay, forming a holding circuit through its armature, and simultaneously energizing said leak indicator and the solenoid to said normally-closed valve to exhaust the line to said lamp.

Other objects and advantages of the invention, relating to the particular arrangement and construction of the various parts, will become apparent as the description proceeds.

Referring to the drawing:

Fig. 1 is a fragmentary vertical sectional View of an exhaust machine embodying my invention, the control circuits being also indicated diagrammatically.

Fig. 2 is a wiring diagram of the embodiment of my invention illustrated in Fig. 1.

Fig. 3 is a wiring diagram corresponding with Fig. 2 but showing a modification.

The present invention may be embodied in any suitable type of exhaust machine, such as used for the progressive evacuation of hollow bodies, and particularly in connection with electric vacuum devices such as fluorescent lamps, incandescent electric lamps, and the like.

Exhaust machines for the above-mentioned purposes are usually provided with two pumps, a preliminary exhaust pump and what is known as a final exhaust pump. The devices to be evacuated are connected with the rst or preliminary pump and exhausted as they travel, that is, they are moved from one port to another while on said pump. The same procedure is followed when the devices are subjected to the second or nal exhaust pump.

The exhaust machine which I prefer to use is oi the type substantially as described and claimed in the Mullan Patent No. 2,113,798, dated April 12, 1938, except as will be specically described in the present application. t will, therefore, be seen that the exhaust machine in which my invention is embodied comprises a rotatable con-` veyor H having a hub l2 desirabi'y carried on a ball or roller bearing 2d and connected to a hollow shaft I3, driven in any suitable manner as by means oi a wheel li carrying index roller it engaged by a cam wheel iii on a shait Vl, driven as by a chain Iii from a suitable source oi' power, such as an electric motor (not shown).

The conveyor il carries a piuraiity of heads I9 which may be genei'aily like those described and claimed in the (austin Patent No. 2,:io,luo, dated september 17, "i940, and each having a rubber exhaust member 2i receiving the exhaust tube 22 oi'` the device to be evacuated, such as a riuorescent lamp i used with :fluorescent lamps, said heads may each carry a mercury doser Zit. Each head is desirabiy provided with a hand lever 25 for eii'ecting the operation thereoi` in gripping or releasing the exhaust tube oi' the device being evacuated.

The conveyor also carries the upper or movable section it oi` the rotatable vacuum valve 21, the lower section 2li of which is mounted on a stationary portion 2Q oi the machine. Said stationary portion also carries the exhaust lines, the preliminary one of which is indicated at 3l, and lines therefrom, one oi which is designated 32, through normally closed valve 33, operated by solenoid 34, to the stationary valve section 28. In the present embodiment, the line 32 which may correspond with that oi position 4 of Fig.

5 of the Mullan Patent No. 2,254,905, of September 2, 1941, also communicates with a U tube 35 carrying mercury 35 and provided with contacts 3l and 3S, uncovered by the mercury when a normal vacuum is maintained in the system, but closed by being submerged in the mercury when the pressure in said system reaches a predetermined point, as due to the development of a leak between the valve 33 and the extreme outer end of the line.

The line 39 between the movable portion 2G of the valve 2l and the head l is desirably pro vided with a trap il and a valve 2, correspond ing with the rubber tube connection t3 and pinch clamp 9i of the Mullan Patent 2,25ll`9'5, previously referred to, normally open but adapted to be closed upon movement of the camm-ing pinch clamp or bell crank lever 3, either manually, or automatically as by engagement of the operating, arm when moving outwardly toward the lever (i3, as viewed5` in Fig. l. The valve when cammed shut by the lever 63, stays in that position` until opened, as will be understood. rhis closing is accomplished upon energization or" the relay 55, supported on stationary rod lili, to draw its armature le to the right and pull the arm @ll oi the bell crank lever 5S in the same direction by connecting link to rotate the operating roller-carrying arm` lil of said crank about its pivotil.

The circuit for eiecting the desired operation of the leak detector is from a suitable source or' power 5l, such as a 110 volt A. C. supply, through spring contacts 5,2 and 53, normally closed but opened every time the shaft il turns, as by engagement ci the cam ell with the upper Contact member 53, through lines 55, and 5l' to contact 33, through the submerging mercury 3e when a leak occurs to contact 3l', through lines 5S, 55, 5i and 52 to electric bell 53, or other leak indicating device, and from there back through line lili' to the other terminal oi the supply.

' ln order to prevent the development of a spark in the mercury U tube 35 when the mercury returns to the normal position illustrated, if at that time the contacts 52` and 53 are closed as illustrated, I provide a relay or holding solenoid t5 which is energized simultaneously with the bellY to draw its armature te' against the action of the spring 'l to close a snorting circuit through line i8 between lines 5* and t; to thereby take the current which would otherwise now through lines 5t, 5S and the contacts t?A and' 33 when connected;

inasmuch as it is desiredA to keep the line 3E' evacuated between the valve and the stationary valve portion so as not to destroy the vacuum of the succeeding line 3% upon corresponding movement ci the movable valve portion il?, energization or the bell or leak indicator is also desirably accompanied by energization of the solenoidl S4 to openthe valve 33 to the vacuum pump, as well` as by energization of the relay d5 through lines ifi and l5 to close the valve [i2 thereby cut ch"- the leaky head lil from the exhaust system.

From the foregoing it will be seen that the operation oi` detecting a leak, as illustrated diagrammatically in Fig. 2, is as follows:

rihe lamp or other device being evacuated is supposed to be at the left end of the exhaust line til termed the sweep. This-line is normally dead or separated from the pump by the nor mally-closed valve 33' controlled' by solenoid 3d. It a leak occurs causing pres-sure in the sweep to move the mercury 3G sufficiently to submerge contacts 3l and 35.2, after the cam Eil allows the switch Est-52 to close, current flows from supply 5l, through contacts 53 and 52, lines 55 and 5S, contacts 33 and 3l, line 5S, relay 65 and line lill, back to supply 5l. The energization oi the relay @5 draws its armature 65 to close a circuit through line ist paralleling and snorting that through the contacts El and 3S. At the same time the circuit through lines @L S2 and t@ operates the bell S3 or other leak detector.

The parallel circuit through lines l2 and 'E3 also energizes the solenoid opening the valve 33, to the pump for restoring the vacuum in the sweep. and attempting to bring the mercury column back to the original or zero level. Even if the opening of the valve 33 restores the vacuum suiciently to uncover the contacts 3l? and 33, there is no spark because of the holding or short circuit through the armature et. It is also clesirabl'e, although not essential,l that the parallel circuit through linesl irl and 'l5 energize relay 55 and thereby effect closing of the normally open valve E3 to out oi the leaky head E9 from the vacuum system, until said head has been ren paired.

rlhe iinal event or the cycle is that; the cam lili separates the contacts 53' andV 52, and the apu paratus is ready to detect a leak in the succeeding head and/cr sweep upon corresponding movenient of the conveyor It and movable valve section 25.

From the foregoing it will' be seen that my leak detector operates on a dead port, or one blocked' from the pump by a closed solenoid valve, the leak causing pressure to, close amercury switch, which during the closure of a circuit by a switch, operated as. by a cam driven from the conveyor for the vacuum head, energizes a solenoid the; armature of which is moved. to establish a short circuit around the mercury switchcjontacts. At the same timev a bell, or other indicator, shows a leak and the solenoid valve` opens while the camoperated switch maintains the, circuit and,.even if the opening of this valve causes the mercury to uncover the contacts therein, there is no spark because of Said short circuit. Upon opening of the cam-operated switch, asA the conveyor turns,r the circuit is deenergizecl and the apparatus is ready to detect another leak.

In case itis desired to. detect a` leak in a lamp on a dead port, or one which. does not evacuate the lamp, while at the same time not losing apllmping position by making theoperation o1 the normally-closed solenoid, valve dependent on` the development of a leak, I use, a compromise arrangement such` as illustrated. diagrammatically in Fig. 3, and in which corresponding parts are designatedy by the` same number with the letter a aflixed.

The lamp,v or otherV device being evacuated isl supposed to b e` atA the left end ot the exhaust line or sweep 39a, as in Fig. 2n. This linev is dead during the"V deteQtOnQf. the leak, but, is

controlled. by a switch; l operated; a. cam. lil, desirably driven along with the conveyor; il.

detection of the leak occurs as in the preceding embodiment.

Specifically, if a leak occurs causing pressure in the sweep to move the mercury 36a suiciently to submerge the contacts 31a and 38a, after the cam bea allows the switch 53-52a to close, current hows from supply Sie through contacts 53a and '52s, relay line 53e, contact 33a, submerging mercury 35a, contact 31a, and lines 56a, 55a and ce, back to supply 51a. The energization of the relay 55e draws its armature 66e to close a circuit through line 68a, paralleling and shorting that through the contacts 3l and 38a. At the same time the circuit through lines Gla, 62a and iii operates the bell 63a or other leak detector. It is also desirable as in the previous instance, although not essential, that a parallel circuit, as through lines Elia and 15a, energize a relay Lilia and thereby effect closing of a normally-open valve, corresponding with valve 43 in F'lg. l, to cut o the leaky head from the vacuum system until said head has been repaired.

Ai'ter the leak has been detected, which occurs during the period illustrated when switch B-- has been opened by cam 18, continued turning oi" said cam allows said switch 16--1'1 to close,

thereby energizing the solenoid 313a through lines iria and isa to open the valve 33a to connect the sweep and corresponding head to the pump, thereby not losing pumping action, except for the short period of time when the switch I6-Ti is open during the leak-detecting operation.

The nal event of the cycle is that the cam trie again separates the contacts 53a and 52a and the apparatus is ready to detect a leak in the succeeding head and/or sweep, upon corresponding movement of the conveyor and movable valve section.

It will thus be seen that my leak detector may also be made to operate on a port which is only dead for a small fraction of the cycle, the leak causing pressure to close a mercury switch which, during the closure of a circuit by a switch operated as by a cam driven from the conveyor for the vacuum head, energizes a solenoid the armature of which is moved to establish a short circuit around the mercury switch contacts. At the same time a bell or other detector shows a leak and the solenoid valve is opened, while the cam-operated switch maintains the circuit, as by another cam-operated switch, to avoid appreciable loss of pumping time. Ii the closing of the switch 'd-fil and the pumping of the sweep causes the mercury valve to uncover the contacts therein, there is no spark because of the short circuit through armature Upon opening of the cam-operated switch 53a-52a, as the conveyor1 turns, the circuit is de-energized and the apparatus is ready to detect another leak.

From the foregoing description it will be seen that I have devised a dead port leak detector which may, if desired, be used and then said dead port made a live port to thereby not lose a pumping position, while at the same time giving a positive indication when leaks are detected and providing a mercury U tube circuit which do-es not deteriorate even with excessive usage. The mercury U tube contacts do not interrupt current and there is thus no tendency to arc, evolve gas, or crack the glass. The mercury column is thus always pumped back to the initial or zero level when the leak is stopped. The bell or other leak detector rings positively from the holding circuit, even if there is a fluctuation or bouncing of the mercury column.

It will also be understood that some of the advantages of my invention may be secured even when using a pressure-sensitive circuitcontrolling device other than a mercury U tube.

Although preferred embodiments of my invention have been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

I claim:

1. In combination with an exhaust machine comprising a conveyor with a head to receive the exhaust tube of a device to be evacuated through a vacuum line, a pressure-sensitive circuit controlling device connected to said line, and with contacts so adjusted that under normal Vacuum conditions said contacts are electrically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes said contacts to be electrically connected, a solenoidcontrolled valve in said line between the said controlling device connection and said exhaust machine, said valve being normally closed to cut ofi said line from` said exhaust machine, means connecting said contacts including an initially open switch, a holding solenoid the armature of which when operated provides a circuit in parallel with said contacts to a source of electrical energy, the solenoid of said valve and a leak indicator, and means for closing said switch as a device being evacuated is indexed for leak-test, whereby when a leak occurs after the device indexes and the initially-open switch closes, the pressure developed in the exhaust line effects an electrical connection of said contacts allowing current to iow therebetween, energizing the holding solenoid to operate its armature, and establish said holding circuit and a circuit through the leak indicator and energize said valve solenoid.

2. In combination with an exhaust machine comprising a conveyor with a head to receive the exhaust tube of a device, to be evacuated through a vacuum line, a mercury U tube connected to said line, and with contacts so adjusted that under normal vacuum conditions said contacts are electrically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes the mercury to connect said contacts, a solenoid-controlled valve in said line between the said mercury U tube connection and said exhaust machine, means connecting the solenoid of said valve and said contacts including a switch, a holding solenoid, the armature of which when operatedl provides a short circuit in parallel with said contacts, to a source of electrical energy and a leak indicator, and means for operating said switch as the conveyor moves, to allow for energization o the solenoid of said valve whereby when a leak occurs, the pressure developed in the exhaust line submerges said mercury U tube contacts, allowing current to flow therebetween, energizing the holding solenoid to operate its armature and establish said short circuit and one through the leak indicator, so that when the circuit opens there is no spark at the mercury U tube contacts.

3. In combination with an exhaust machine comprising a rotatable ,conveyor with a head including a rubber conduit to receive the exhaust tube of a device to be evacuated through a vacuurn line and an arm to effect compression of said conduit to grip said exhaust tube therein, a normally-closed solenoid-operated valve in the vacnum line to; said head when said conveyor isv in one position, a mercury U tube connected to. said line, and with contacts so adjusted that under normal vacuum conditions. said contacts are electrically disconnected, while when a lea-k develops said line the increase in pressure beyond a predetermined point causes the mercury to submerge said contacts, means; connecting said contacts inc'luding av cam-actuated switch and a vholding solenoid, the armature ofV which when operated provides a circuit in parallel with said contacts, to a source of electrical energy, and a leak indicator and the solenoid or said valve in parallel with one another, but in series with said contacts and armature, whereby when the cam-actuated switch is closed and a leak occurs, the` pressure developed in the exhaust line submerges said mercuryV U tube contacts and causes; a current to flow therebetween, energizing the holding solenoid to operate its armature and establish a cirf cuit through the leak indicator and solenoid of said valve, to. restore the vacuum in said line and Yopen the mercury U tube contacts without a spark, vuntil the cam opens its switch and the apparatus is ready to detect another leak.

4. In combination with an exhaust mach-ine comprising a conveyor with a head to receive the exhaust tube of a device to be evacuated through a vacuum line, a relay-controlled normallympen valve near said head and in said line, a mercury U tube connected to said line, and with contacts so adjusted that under normal vacuum conditions said contacts are electrically disconnected, while when a leak develops in said line the increasev in pressure beyond a predetermined point causes the mercury to submerge said contacts, a norm-allyclosed solenoid-operated valve in said vacuum line on the opposite side of said U tube connection from said normally-open valve, means connecting through said contacts, the solenoid of said Valve including a switch, a leak indicator, and the relay of saidl normally-Open Valve, to a source Gi; electrical energy, and means for operating said switch as the conveyor moves, to allow for energiaaticn of the solenoid of said valve whereby when a leak occurs, the; pressure 'developed in the exhaust line submerges said mercury U tube contacts, causes current to ilow therebetween and establish a circuit through the leak indicator and the relay or said normally-open Valve to cut off said head` from the vacuum line, and the solenoid` 0f said normally-closed Valve, c

5. In combination with an exhaust machine comprising a conveyor with a head to receive the exhaust tube of a device to be evacuated through a vacuum line, a relaycontrolledl normal y-opcn valve near said head and in said line, a mercury U tube connected to said line, and with contacts so adjusted that under normal vacuum cond vls said contacts are electrically disconnected, while when a leak develops in line the increase in pressure beyond a predetermined point causes the mercury to. submerge said contacts, a normallyclosed solenoid-operated valve in said vacuum line on the opposite side of U connection from said normally-open valve, means including a switch connecting through said' contacts, the solenoid of said valve, a holding solenoid, the armature of which when operated provides a short circuit in paralleli h said contacts, a leak indicator, and the relay of said normally-open valve, to a source of electrical energy and means for operating said switch as the conveyor moves, to allow for energization of the solenoid of said valve whereby when a leak occurs, the pressure holding sole developed the exhaust line submerges said mercury U tube contacts, causes current to` now therebetween, energizing the holding solenoid to operate its armature and establish a circuit through the leak indicator, the relay of said normally-open valve to. cut. off said head ironl the vacuum line, andthe solenoid of said norm-ally-a closed. valve.

6. In combination with an exhaust machine comprising a conveyor with a head to` receivethe exhaust tube ci a device to bel evacuatedthrough a Vacuum line, a normally-,closed solenoid-operated valve in the Vacuum line, a pressure-sensi tive circu-itecontrolling device connected to, said line, and with contacts so. adjusted that under normalvacuum conditions said contacts are elec,- trically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes said contacts to, be electrically connected, a holding solenoid, a leak indicator', meansv connecting. said contacts. including a cam-actuated switch and said holding solenoid, the armature ci' which when operated provides a short circuit aaraliei with said contacts, and said leali indicator in parallel, to a source of electrical energy, whereby when a leak occurs,l .the raves-sureI deyeioped in the exhaust line eects an electrical connection of said contacts, allowing current to now therebetween, energizing id to operate, its, arm 1re, and establish a circuit through theA leak indicator, until the cam opens, the. circuit, and means ier finally opening tl: solenoic-cnerated valve to rc.- store the vacuum said; System.

'7. In con'ibir-iaV n with an exhaust machine comprising a conveyor with a head to receitje the exhaust tube oi a device to be evacuated through a vacuum line, a normalty-closed solenoid-operated Valve in the vacuum line, a mercuryV U V tube connected to said line, and with contacts,A connected through switch means operable as the conveyor moves,y Aand so adjusted that under normal vacuum. CGnditions said contacts are electrically disconne cted,l while when a leak develops in said line the increase in pressure beyond a predetermined point causes the mercury to submerge and connect said contacts, a holding solenoid, a leak indicator, means connecting said contacts includingT said switch means,l and holding solenoid, the armature of which when operated provides a short circuit inparallel with said contacts, and said leak indicator and valve solenoid in parallel to said source of electrical energy, wherebyy when a device is indexed upon movement of said conveyor and a leak occurs, the pressure developed in the exhaust line closes said mercury U tube contacts, allowing current to now therebetween, energizing the holding solenoid to operate its armature and establish a circuit through the leak indicator, until the circuit is opened, by said switch means, and the solenoidmperated valve opens to restore the vacuum in system.

8. In combination with an exhaust machine comprising a conveyor with a head to receive the exhaust tube of a device to be evacuated through a Vacuum line, a normally-closed controlled valve in the vacuum line to said head when said con- Veyor is in one position, a mercury U tube connected to said line, and with contacts so adjusted that under normal vacuum conditions said contacts are electrically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes the mercury to submerge said contacts, means connecting said contacts, including a switch, operating as the conveyor moves, and a holding solenoid, the armature of which when operated provides a circuit in parallel with said contacts, to a source of electrical energy, and a leak indicator and the control means of said valve in parallel with one another, but in series with said contacts and armature, whereby when the conveyor moves and the switch is closed, the pressure developed in the exhaust line, upon the occurrence of a leak, submerges said mercury U tube contacts and causes current to flow therebetween, energizing the holding solenoid to operate its armature and establish a circuit through the leak indicator and control means of said valve, t0 restore the vacuum in said line and open the mercury U tube contacts without a spark.

9. In combination with an exhaust machine comprising a conveyor with a head connected to a vacuum line to receive the exhaust tube of a device to be evacuated there-through, a normally-closed solenoid-controlled valve in the vacuum line to said head when said conveyor is in one position, a mercury U-tube connected to said line and with contacts so adjusted that under normal vacuum conditions they are electrically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes the mercury to submerge said contacts, means connecting the solenoid of said valve and said contacts, including a switch operating as the conveyor moves, and a holding solenoid, the armature of which when operated provides a circuit in parallel with said contacts, to a source of electrical energy, and a leak indicator in series with said contacts and armature, whereby when the conveyor moves and the switch is closed the pressure developed in the vacuum line, upon the occurrence of a leak, submerges said mercury U- tube contacts and causes current to flow therebetween, energizing the holding solenoid to operate its armature and establish a circuit through the leak indicator.

10. In combination with an exhaust machine comprising a conveyor with a head connected to a vacuum line to receive the exhaust tube of a device to be evacuated therethrough, a normallyclosed solenoid-controlled valve in the vacuum line to said head when said conveyor is in one position, a mercury U-tube connected to said line and with contacts so adjusted that under normal vacuum conditions they are electrically disconnected, while when a leak develops in said line the increase in pressure beyond a predetermined point causes the mercury to submerge said contracts, means connecting said contacts, including a switch operating as the conveyor moves, and a holding solenoid, the armature of which when operated provides a circuit in parallel with said contacts, to a source of electrical energy, :and a leak indicator in series with said contacts and armature, whereby when the conveyor moves and the switch is closed the pressure developed in the vacuum line, upon the occurrence of a leak, submerges said mercury U-tube contacts and causes current to flow therebetween, energizing the holding solenoid to operate its armature and establish a circuit through the leak indicator, and means including another switch closing after the iirst-mentioned switch as the conveyor moves, connecting the solenoid of said valve to said source of electrical energy, to restore the vacuum in said line after the operation of the leak detector.

JOHN M. CAMPBELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,651,865 Blake et al Dec. 6, 1927 1,933,322 Fagan Oct. 31, 1933 1,951,142 Foulke Mar. 13, 1934 2,025,579 Donovan et al Dec. 24, 1935 2,162,209 Truther June 13, 1939 2,254,905 Mullan Sept. 2, 1941 

